CUCV '400' tranny will not shift out of 1st gear - what should I check first?

[DaninNM]

I have a CUCV with decent mileage but the transmission will not shift into 2nd or 3rd.....just says in 1st gear. ANYONE HAVE SUCH A PROBLEM? Looking for a fix or suggesitons OR a takeout CUCV transmission. price and location in first email pleasel

 

[bajaman]

Check the vacuum line giing to the modulator on the transmision passenger side, needs to be plugged in, buy a new one easy fix

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[bajaman]

A new modulator

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[Tow4]

Bypass the shift modulator that is attached to the throttle and plug the vacuum line from the vacuum pump directly into the line going to the transmission. This will make the transmission shift to third gear very fast. You can manually shift up through the gears on a test drive and verify they work.

 

[DaninNM]

Does the shift modulator go bad? Where can I buy a new one - Autozone, NAPA, - is it a standard GM transmission part?

 

[NDT]

Yes they go bad and the part is available anywhere. Also if you have no vacuum available, the vacuum pump may have failed. If the post #4 test does not correct the problem, the plastic governor gear is likely stripped.

 

[Mainsail]

Don't buy anything until you check the vacuum lines first.

It might be an easy fix, like mine was.

 

[Curtisje]

Is it full of fluid?

 

[DaninNM]

has a new box on the side, tranny is full of fluid - will test the vacuum lines on Friday! thanks all!

 

[DAVEM939]

Hate to chime in late but there is a vacuum valve regulator in the throttle linkage. google this to see if you have one ??? they go bad often . but do all the above also. This should cover every thing in the tm's and under the sun just saying. Good luck.

 

[MrMikey4026]

Governor gear. Under small cover near rear of transmission, four 1/2" bolts.

 

[socalsrt]

I second MrMikey426, it is a stripped out governor gear. Passenger side towards the rear of the transmission there is a square cover being held on with four bolts. Take the cover off and slide the governor out. The plastic gear on the end is most certainly stripped. I ended up buying one off ebay. Just search for Turbo 400 Governor Gear. Very easy and inexpensive repair. Mine had the clearish looking white gear in it.....

 

[DaninNM]

checking that in the MORNING - will report back the result - many thanks all!!!!!!!

 

[rumplecat]

?

 

[Rocknus]

I have a CUCV with decent mileage but the transmission will not shift into 2nd or 3rd.....just says in 1st gear. ANYONE HAVE SUCH A PROBLEM? Looking for a fix or suggesitons OR a takeout CUCV transmission. price and location in first email pleasel

I know this is an old post and you probably solved your problem by now, but I just experience the same problem... Stuck in first.
If I got going fast enough it would kick into 2nd, most likely due to the governor. I couldn't get the revs high enough to catch 3rd.
I went through everything!
Checked vacuum at pump... Was good at 22 straight out of the pump.
Checked vacuum on the "out" side of the vacuum valve on the IP. Had a steady 10 at idle and it decreased as expected when throttled up. Frankly, I think 10 is a little low. I have a spare valve that puts out about 13, but that wasn't the issue anyway.
I got the same vacuum results at the vacuum modulator end that I got directly out of the valve at the IP.
Checked vacuum modulator. Not leaking. Changed it our for new anyway. Still stuck in first gear.
Checked the governor... It looked OK. A little old and brittle so I replaced it with new just in case because it was cheap. Still stuck in first gear.

Now I was all set with troubleshooting so I got mad at it and just swapped the whole transmission out for a known good one from another running truck... STILL STUCK IN FIRST GEAR!!! WTF!?!?

So now I know this problem is not transmission related. There's no way I got 2 transmissions that do the same exact thing.

Now I'm racking my brain. I kept thinking about how I was just driving along when it suddenly went into first gear and wouldn't come out. I remember that there was no loud bang, or grinding or any other sound of mechanical failure. It simply downshifted to first and wouldn't come out. I had checked and/or replaced everything, even the transmission itself. What could it be?!?!

Then it hit me... The kickdown! If that is activated, it will keep you "kicked down" in first gear. That's what it's for... Kicking down from 2nd to 1st when the pedal is slammed.
I unplugged the single wire from the driver's side of the transmission and I'll be dipped! THAT WAS IT!
One stupid wire!!!!! Unplugged and it shifted fine. Plugged in and it was stuck in first.
One stupid wire that I put right back onto the new transmission like a dummy!
I feel stupid for not starting right off troubleshooting that! Shame on me! LOL!

Anyway... Check the kickdown first then move on to all the other stuff.
I'm making a video of the whole thing. Should be up soon. Hope this helps someone. I know I struggled to find the correct answer to this issue.

 

[MrMikey4026]

I know this is an old post and you probably solved your problem by now, but I just experience the same problem... Stuck in first.
If I got going fast enough it would kick into 2nd, most likely due to the governor. I couldn't get the revs high enough to catch 3rd.
I went through everything!
Checked vacuum at pump... Was good at 22 straight out of the pump.
Checked vacuum on the "out" side of the vacuum valve on the IP. Had a steady 10 at idle and it decreased as expected when throttled up. Frankly, I think 10 is a little low. I have a spare valve that puts out about 13, but that wasn't the issue anyway.
I got the same vacuum results at the vacuum modulator end that I got directly out of the valve at the IP.
Checked vacuum modulator. Not leaking. Changed it our for new anyway. Still stuck in first gear.
Checked the governor... It looked OK. A little old and brittle so I replaced it with new just in case because it was cheap. Still stuck in first gear.

Now I was all set with troubleshooting so I got mad at it and just swapped the whole transmission out for a known good one from another running truck... STILL STUCK IN FIRST GEAR!!! WTF!?!?

So now I know this problem is not transmission related. There's no way I got 2 transmissions that do the same exact thing.

Now I'm racking my brain. I kept thinking about how I was just driving along when it suddenly went into first gear and wouldn't come out. I remember that there was no loud bang, or grinding or any other sound of mechanical failure. It simply downshifted to first and wouldn't come out. I had checked and/or replaced everything, even the transmission itself. What could it be?!?!

Then it hit me... The kickdown! If that is activated, it will keep you "kicked down" in first gear. That's what it's for... Kicking down from 2nd to 1st when the pedal is slammed.
I unplugged the single wire from the driver's side of the transmission and I'll be dipped! THAT WAS IT!
One stupid wire!!!!! Unplugged and it shifted fine. Plugged in and it was stuck in first.
One stupid wire that I put right back onto the new transmission like a dummy!
I feel stupid for not starting right off troubleshooting that! Shame on me! LOL!

Anyway... Check the kickdown first then move on to all the other stuff.
I'm making a video of the whole thing. Should be up soon. Hope this helps someone. I know I struggled to find the correct answer to this issue.

Unplug the wire going to the transmission to see if it shifts.
The downshift is electric, if the switch is shorted it will cause that symptom.